Why Does Greenwich Mean Time? Podcast Episode
Hello readers old and new, this week we are back again with an issue with Pub Convos. The clocks in Britain are scheduled to be going back an hour on the 31st of October and the time zone changes from British Summer Time (BST) to Greenwich Mean Time (GMT). In this issue, I’ll talk about why this happens and how GMT came to be the standard time in the United Kingdom.
Greenwich Mean Time (GMT)
Traditionally a day was calculated when the sun crossed the Greenwich Meridian Line at noon (at its highest point in the sky). A meridian line is an imaginary line that runs directly from the North Pole to the South Pole. There are many meridians in the world, but the British decided to use the one that passes through Greenwich.
Prior to the introduction of a standard time, most places had a local time which relied on the movement of the sun. This was not a big deal as a couple minutes made a miniscule difference when transport and communications were slow anyway. However, the introduction of the railway network created the requirement for a standard time that timetables could be based on. Therefore, the railway network adopted GMT across the network.
Now places have two times, a local time and a ‘railway time’ and slowly this became annoying, and it was decided that GMT was to be the standard across all of the United Kingdom. Keen astronomers amongst you will now tell me calculating a day based on the time the sun crosses a location is wildly inaccurate as the earth is tilted and the orbits are elliptical rather than a perfect circle and you would be right. This is where the ‘M’ part of GMT comes in, ‘M’ stands for mean as in average, so GMT is actually the average of each solar day across the year.
Clocks Going Backwards and Forwards?
Every year the clocks go forward in March and go backward in October in the UK. This is due to something called daylight saving. This is done because the less fortunate of us who don’t live somewhere near the equator don’t get equal hours of daylight and night-time due to the orientation of the earth. The sun sets at around 5:40 pm at the time of writing and it only gets earlier the deeper we get into winter.
Once the clocks go backwards in October, there is more daylight in the mornings, but sunsets get earlier. While in March when the clocks go forwards, you lose an hour of daylight in the mornings but get to have more daylight in the evenings.
Why? That’s because some old bloke named William Willett despite not inventing the concept of daylight saving strongly advocated for it in the late 19th century so that he could play golf in the evenings for longer during summertime. He is apparently also the great great grandfather of Coldplay frontman Chris Martin. A more sensible reason was that it was introduced during the 1st World War by the government in an attempt to save coal. Whichever one you choose to believe, whenever you are late you can just say you were in the wrong time zone.